What it is and what it does
The Siemens SENTRON 3VA1112-6MH36-0AA0 is a 3-pole molded case circuit breaker (MCCB) designed specifically for starter protection — meaning it's built to sit ahead of a motor contactor and handle the high inrush without nuisance tripping, while still protecting the motor branch against short circuits. It carries a TM120M thermal-magnetic overcurrent release, rated 125 A continuous at 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C — so if your panel ambient runs hot, you need to factor that curve into your load calculation, not just the 125 A nameplate. Breaking capacity is voltage-dependent: 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, and 7.5 kA at both 500 V and 690 V. That 220 kA figure at 240 V tells you this breaker is designed for high-fault-current installations — typically large transformer-fed switchboards or industrial distribution where the available fault current is substantial.
Integration and mounting
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint that fits most Siemens SENTRON panelboards and distribution blocks. The front face carries IP40 protection, so it's fine for general indoor panel use but not for washdown environments. Rated insulation voltage is 800 V, and the maximum power loss at rated current is 28.1 W — worth checking if you're packing multiple breakers in a small enclosure, since that heat adds up. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. No undervoltage release, no voltage trip indicator, no ground-fault monitoring — this is a straight thermal-magnetic breaker with no auxiliaries built in.